This study of advanced readers in Reading First (RF) classrooms was part of a larger evaluation of one state's RF implementation. The study's purposes were to (a) assess the longitudinal growth of advanced primary readers as compared with their non-advanced-reading peers over a 3-year timeframe and (b) determine the degree to which RF classrooms addressed the reading needs of advanced primary readers. Archival data sources included RF scaled scores, classroom observations, and interviews with teachers, coaches, and principals. Using multilevel growth modeling, results indicated that all readers grew; however, advanced readers grew the least, with the average of the group going from the 97th national percentile rank (NPR) in the spring of kindergarten to the 83rd NPR in the spring of their second-grade year. Qualitative findings revealed four themes: (a) Strict adherence to adopted basal readers defined program fidelity, (b) compromises in curriculum and instruction limited opportunities for advanced readers, (c) degree of fit between the core basal readers and advanced readers resulted in lack of challenge, and (d) varied understandings (and misunderstandings) surrounding differentiated instruction led to limited rigor for advanced readers. Recommendations are offered to help practitioners and researchers ensure that the needs of advanced readers in proposed federal and state education regulations and initiatives are considered rather than only focusing on struggling students.